【摘要】 利用超声疲劳低-高应力两步变幅加载技术研究了JIS SUJ2高强轴承钢疲劳断口上GBF(granular bright facet)内裂纹萌生与扩展规律。结果表明,随外加应力幅增加GBF尺寸减小,固定应力幅下的GBF尺寸为恒定值,与夹杂物尺寸无关;且在固定应力幅下,N f∝A槡inc-8,疲劳寿命N f随着夹杂物尺寸的增加而降低。研究表明,GBF形成于疲劳初期(在105周次左右,相应于小于1%的总寿命),随循环周次的增加,GBF尺寸基本不增加,直至接近最终疲劳寿命时(超过90%总寿命)GBF裂纹快速扩展直到最终尺寸。更多还原

【Abstract】 Fatigue crack initiation and growth behavior in the granular bright facet(GBF) area of a high strength bearing steel SUJ2 were studied by ultrasonic fatigue testing under low-high two step variable loading.The results show that the GBF size reduces with increasing applied stress amplitude,and that the GBF size at a given stress amplitude is a constant which is independent of inclusion size.The fatigue life at a given stress amplitude,which is proportional to-8 power of the inclusion size at the crack origins,reduces with increasing inclusion size.It is shown by two-step variable amplitude loading tests that GBF is formed at the earlier stage of fatigue(approximate 105 cycles corresponding to less than 1% total fatigue life in the regime N f ≥107cycles) and propagates hardly until near to the final life(more than 90% total fatigue life),and the GBF crack will rapidly propagate to the ultimate size in short time.更多还原